Rotary electrical switches comprising a rotary contact and a number of stationary contacts are known in general. Such switches may comprise a plurality of layers, each layer comprising a rotary contact and a number of stationary contacts, for concurrently switching a plurality of currents.
Electrical rotary switches are predominantly used for switching DC currents. A known problem with DC currents is that when opening a switch by separating the switch contacts a spark builds between the contacts. A spark may also occur when switching off an AC current in a moment of non-zero current flow. The spark produces an explosion-like hot plasma cloud which generally is erosive and conductive. The plasma cloud or spark plume may thus cause damage to nearby objects and/or cause or lead to short-circuiting. The sparks and their effects increase with increasing switched power.
The traditional solution for switching larger powers is to increase the size of the switch. This increases contact distances and thus reduces chances of short circuits due to sparking or voltage creep over surfaces.
Further, a rotary switch typically comprises a rotation control mechanism comprising a locking spring for operably rotating the rotary contact or contacts rapidly between a first position for closing the switch and a second position for opening it. The forces acting on the rotation control mechanism and on the one or more portions therein holding the locking spring may be considerable. These forces may increase when increasing the size of the switch, requiring a stronger construction and/or more material. This adversely affects the ease of operation of the switch.
There is a continuous demand for both increased switchable power and smaller switches. Furthermore, safety requirements tend to become tighter over time.
Consequently, there is a desire for an improved rotary electrical switch.